closes #1569, #3731: refactored dependent metho...

closes #1569, #3731: refactored dependent method types to get rid of
debruijn indices and use singleton types instead.

this is the core of the dependent types refactoring, no implicit or
inference changes

(one baffling discovery: resultType should drop annotations that don't subclass TypeConstraint, even in the trivial case... wow -- thanks to Tiark for helping me figure it out on a terrace in Barcelona
TODO: probably need a more principled approach to the propagation of plugin type-annotations)

review by odersky

1 files changed, 8 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 01f1d2c211..b175cb24ee 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -55,7 +55,6 @@ trait ScalaSettings extends AbsScalaSettings with StandardScalaSettings {
   val noassertions  = BooleanSetting    ("-Xdisable-assertions", "Generate no assertions and assumptions")
   val elidebelow    = IntSetting        ("-Xelide-below", "Generate calls to @elidable-marked methods only if method priority is greater than argument.",
                                                 elidable.ASSERTION, None, elidable.byName.get(_))
-  val Xexperimental = BooleanSetting    ("-Xexperimental", "Enable experimental extensions")
   val noForwarders  = BooleanSetting    ("-Xno-forwarders", "Do not generate static forwarders in mirror classes")
   val future        = BooleanSetting    ("-Xfuture", "Turn on future language features")
   val genPhaseGraph = StringSetting     ("-Xgenerate-phase-graph", "file", "Generate the phase graphs (outputs .dot files) to fileX.dot", "")
@@ -79,10 +78,18 @@ trait ScalaSettings extends AbsScalaSettings with StandardScalaSettings {
   val Xshowobj      = StringSetting     ("-Xshow-object", "object", "Show object info", "")
   val showPhases    = BooleanSetting    ("-Xshow-phases", "Print a synopsis of compiler phases")
   val sourceReader  = StringSetting     ("-Xsource-reader", "classname", "Specify a custom method for reading source files", "scala.tools.nsc.io.SourceReader")
+
   val Xwarnfatal    = BooleanSetting    ("-Xfatal-warnings", "Fail the compilation if there are any warnings.")
   val Xwarninit     = BooleanSetting    ("-Xwarninit", "Warn about possible changes in initialization semantics")
   val Xchecknull    = BooleanSetting    ("-Xcheck-null", "Emit warning on selection of nullable reference")
 
+  // Experimental Extensions
+  val Xexperimental = BooleanSetting    ("-Xexperimental", "Enable experimental extensions") .
+                          withPostSetHook(_ => List(YdepMethTpes, YmethodInfer) foreach (_.value = true)) //YvirtClasses,
+  val YdepMethTpes  = BooleanSetting    ("-Ydependent-method-types", "Allow dependent method types")
+  val YmethodInfer  = BooleanSetting    ("-Yinfer-argument-types", "Infer types for arguments of overriden methods")
+  val YvirtClasses  = false // too embryonic to even expose as a -Y //BooleanSetting    ("-Yvirtual-classes", "Support virtual classes")
+
   /** Compatibility stubs for options whose value name did
    *  not previously match the option name.
    */